A bibliometric analysis of research on Ebola in Science Citation Index Expanded

HOW TO CITE: Pouris A, Ho YS, A bibliometric analysis of research on Ebola in Science Citation Index Expanded. S Afr J Sci. 2016;112(3/4), Art. #2015-0326, 6 pages. http://dx.doi.org/10.17159/ sajs.2016/20150326 An unprecedented outbreak of the Ebola virus in 2014 claimed more than 1000 lives in West Africa and the World Health Organization declared a global public health emergency. This outbreak will undoubtedly promote additional research related to the Ebola virus and will create debate related to experimental drugs. This article identified the quantum of research in the field since 1991; the scientific disciplines that contributed to the field; the countries, organisations and authors that supported such research and the most cited articles. An increasing trend in annual production during 1991–2013 was observed. Journal of Virology, Journal of Infectious Diseases, and Virology were the three most productive journals in the field. Similarly, the field of virology dominated the 73 categories in which the Ebola research was classified. A total of 63 countries contributed to Ebola-related research, led by the USA. The most productive institutions were the United States Army Medical Research Institute of Infectious Diseases, the Centers for Disease Control and Prevention, and the National Institute of Allergy and Infectious Diseases. African countries were more likely to be involved in international collaboration than independent research. The most influential article exhibited a notable citation pattern and presented global trends in emerging infectious diseases.


Introduction
The worst Ebola outbreak in recorded history claimed more than 1000 victims 1 by 20 August 2014. It affected West Africa and Nigeria directly, but fears of its spreading affected the rest of the World. The World Health Organization called an international public health emergency and launched a USD 100 million response plan. 2 The 2014 Ebola outbreak was first diagnosed in the remote southeastern area of Nzerekore in Guinea in February 2014, but subsequently spread to neighbouring Liberia, Sierra Leone and Nigeria. 3 Ebola's origin is not known, but it is suspected that it is transmitted through forest bats. It can be transmitted between humans by touching sufferers or through body fluids. 4 The isolation of the aetiologic agent of Ebola haemorrhagic fever was reported for the first time during 1977. 5 According to the US Centers for Disease Control and Prevention, 4 since 1976 there have been 34 known outbreaks of Ebola. Before the latest outbreak, the deadliest episode was the first recorded outbreak in 1976 which killed 280 people in Central Africa. 4 Apart from the mobilisation efforts to contain the virus and develop a relevant vaccine, the issue raised a number of ethical questions, as an experimental drug was used for two US health workers and not for African patients. 1 The objective of this article is to report the results of an investigation aimed at mapping the research efforts related to Ebola virus internationally using scientometric techniques. These assessments are increasingly used as the basis for monitoring research performance of particular scientific disciplines and the support of appropriate policy actions. More specifically, the purpose of the study was to identify the state of Ebola virus research internationally and plot trends over time, to identify the institutions which undertake Ebola virus research and to pinpoint the scientific specialities which are emphasised in the field. The results of the investigation could possibly constitute benchmarks for monitoring the evolution of the research in this field and the impact of the outbreak on research efforts internationally.

Document type and language of publication
During the period under examination, 1623 documents from 12 document types were indexed. Of these documents, 70% were research articles, 10% reviews, 7.8% news items, 4.7% meeting abstracts, 4.5% editorial material, 3.9% proceedings papers, 1.6% letters, 0.62% corrections, 0.49% notes, 0.43% reprints, 0.12% book chapters and 0.062% biographical-items. The percentage of articles related to Ebola was lower than general medically-related fields, such as asthma in children 14 and Japanese lung cancer research 15 , but was much higher than special infection research of severe acute respiratory syndrome 16 and Helicobacter pylori 17 . It was also noticeable that the document type, 'news items', took the third position. A high percentage of news items could also be found in severe acute respiratory syndrome (SARS) research 16 , which was studied after its outbreak in 2003 18 .
The 1133 articles were analysed more thoroughly and revealed that the majority (96%) were in English. The second most popular language was Russian with 2.2%, followed by French (11 articles), German (three articles) and Spanish (one article).

Web of Science categories and journals
Distribution of Web of Science categories and journals have been studied in research topics. 19 In 2013, the Journal Citation Reports (JCR) indexed 8474 journals with citation references across 175 scientific disciplines in the science edition. The articles on Ebola were published in journals listed in 73 Web of Science categories in the science edition.
During the period of the study, five categories published more than 100 articles, with the category virology contributing the most with 426 articles (38% of 1132 articles), followed by immunology (226 articles; 20%), microbiology (218; 19%), infectious diseases (203; 18%), and biochemistry and molecular biology (107; 9.5%). In 1999, 2007, and 2011, there were citation peaks in the categories immunology, microbiology and infectious diseases ( Figure 2). The Ebola set of articles was further analysed according to the journals in which they were published. In total, 1133 articles were published in a range of 282 journals. According to Bradford's Law of Scattering 22 , the journals were sorted in descending order in terms of number of articles, and then divided into three 'zones'. Zone 1 represented the most productive one-third of the total articles, with three (1.1%) of 282 journals. Zone 2 represented the next most productive one-third of total articles, with 28 (9.9%) of 282 journals (9.9%), and Zone 3 represented the least productive one-third of total articles with 251 (89%) of 282 journals. The three most productive core journals were Journal of Virology, which published the most proteome articles (172; 15% of 1133 articles), followed

Publications of country and institution
Excluding 11 articles without affiliation information of authors in Web of Science, there were 1122 articles with author information. Of these 1122 articles, 705 (63%) were single country articles and 417 (37%) were internationally collaborative articles. The top 10 countries, taking 93%, are listed in Table 1 under six indicators: total number of articles, single country articles, internationally collaborative articles, first author articles, corresponding author articles, and single author articles. 23 Of the articles ranked in the list of top 10 publications, 2 were from American countries, 5 were from European countries, 2 were Asian and 1 was from an African country, Gabon. Except for Italy, the Group of Eight (G8) (France, Germany, Italy, Japan, the UK, the USA, Canada, and Russia) were ranked in the top 7. This is no coincidence, as the earliest Ebola research took place in these industrialised countries

Highly cited articles
The total number of times an article was cited from Web of Science Core Collection since its publication to the end of 2013 (TC 2013 ) was estimated. 13 TC 2013 , an accumulative number, could reach a large value as long as the time span is long enough. The citation lives of the top 10 articles (TC 2013 >250) are shown in Figure 3. The only 1 article that kept a sharply increasing citation trend after its publication was 'Global trends in emerging infectious diseases' 26 published in by 7 authors from Wildlife Trust in China, Zoological Society of London in the UK, Columbia University in the USA, and University of Georgia in the USA. In this article, 335 emerging infectious diseases (EID) events were analysed and the authors demonstrated nonrandom global patterns between 1940 and 2004. A conclusion was that EID events are dominated by zoonoses (60.3% of EIDs), with the majority of these (71.8%) originating in wildlife (for example, severe acute respiratory virus, Ebola virus), and increasing significantly over time. Global trends in emerging infectious diseases' 26 not only discussed Ebola but also other emerging infectious diseases. Table 3     The Ebola crisis has raised a number of issues that are subject to further research. How can the authorities decide on the resources to be spent on various diseases and related prevention activities? A controversy about drug testing in Africa and who should benefit for limited experimental drugs are also complexities facing public health authorities internationally outside the critical issue of how to control the disease and prevent its spreading to other countries. Similarly, it will be interesting to identify how the outbreak will affect research activities in the field in the foreseeable future.